The field of the present disclosure relates generally to turbine engines and, more specifically, to a fuel-air mixer for use with a combustor assembly.
Rotary machines, such as gas turbines, are used to generate power for electric generators. Gas turbines, for example, have a gas path which typically includes, in serial-flow relationship, an air intake, a compressor, a combustor, a turbine, and a gas outlet. Compressor and turbine sections include at least one row of circumferentially spaced rotating buckets or blades positioned within a housing. At least some known turbine engines are used in cogeneration facilities and power plants. Such engines may have high specific work and power per unit mass flow requirements. To increase the operating efficiency, at least some known turbine engines, such as gas turbine engines, may operate with increased combustion temperatures. Generally, in at least some known gas turbine engines, engine efficiency increases as combustion gas temperatures increase.
However, operating known turbine engines at higher temperatures may also increase the generation of polluting emissions, such as oxides of nitrogen (NOX). Such emissions are generally undesirable and may be harmful to the environment. At least some known turbine assemblies facilitate reducing NOx emissions by using pre-mixing technology. Pre-mixing fuel and air facilitates inhibiting the temperature of combustion gases such that the combustion temperature does not rise above the threshold where NOx emissions are formed.
Natural gas is used in at least some known pre-mixers. Natural gas is a fuel mainly composed of methane that has a tendency to burn cleaner compared to other known hydrocarbon fuels. Due to the limited availability of natural gas, the use of non-conventional fuels may be desirable. However, non-conventional fuels such as weak natural gas, for example, contain up to 60-70% of inert compounds by volume. As such, non-conventional fuels have a modified Wobbe index (MWI) number outside of the MWI range that can be accommodated by known fuel nozzles.